(1) Field of the Invention
The present invention relates to a heat insulating laminate.
The main application of the heat insulating laminate of the present invention is as a heat insulating material, but it is not necessarily limited to this. For example, the heat insulating laminate of the present invention may be used as a soft wall material or a decorating material for a building, or as a separate storage material for fluids.
(2) Description of the Prior Art
An insulating material which utilizes the shrinkage of a contractile thin film is disclosed in U.S. Pat. Nos. 3,574,109 and 3,655,502.
This disclosure of the prior art, however, only refers to the partial bonding of a noncontractile metal thin film with a contractile thin film and does not teach continuous multi-lamination of noncontractile metal thin films. The metal thin films are stacked for improving the heat insulating effects. Although direct contact between the metal surfaces may be advantageously avoided, the number of reflective metal thin films among the total number of the films is increased. This still leaves much room for improvement with respect to performance, cost, and easy workability. When the continuous multi-lamination of the noncontractile reflecting metal thin films in which noncontractile reflecting metal thin films, for example, aluminum foils are directly stacked one upon another is adopted, these properties may be improved. However, good results are not obtainable with respect to separation between the respective films and good lamination characteristics. When thin aluminum foils are continuously laminated, adjacent foils will have congruent wrinkles as if they were one aluminum foil. They fail to provide sufficient space therebetween, that is, thickening effects, even if they are partially separated. The Japanese Laid-Open Patent Application No. 60850/75 has been proposed to provide an improved heat insulating laminate. This application, however, only discloses multilayered spot-bonded foils according to which the interior of the air bag is spot-bonded and does not concentrate on the shrinkage of the contractile films. Thus, it has been proposed that both sides be pulled to thicken the laminate.